According to the present invention, a process is provided for reacting an aniline compound with a lactone. This reaction is referred to herein as an "alkylation" reaction. The term "alkylation" is thus used herein to refer to an addition reaction between an aniline and a lactone.
The compounds prepared in accordance with the process of the present invention are especially useful as fungicides.
Commonly assigned U.S. Pat. No. 3,933,860 discloses the preparation of lactone-substituted compounds wherein in a first step the following reaction is carried out ##STR1## As can be seen from the examples in U.S. Pat. No. 3,933,860, the aniline reaction is carried out in the absence of water. Thus, in Example 1, dichloroaniline is reacted with alpha-bromo-gamma-butyrolactone at 110.degree. to 145.degree. C. to give a solid mixture of 3,4-dichloroaniline hydrobromide salt and 3-(N-3,4-dichlorophenylamino)-gamma-butyrolactone. The mixture thus obtained was treated with methylene chloride and filtered to separate the salt as a solid. The filtrate was evaporated to thereby remove the methylene chloride and yield the desired aniline-lactone reaction product.
In Example 2 of U.S. Pat. No. 3,933,860, dimethylaniline was reacted with alpha-bromo-gamma-butyrolactone inthe presence of sodium carbonate and dimethylformamide. The reaction time was 21 hours. After the reaction, the reaction mixture was diluted with water at room temperature to remove the dimethylaniline hydrobromide salt into the aqueous phase and the reaction mixture was also extracted with benzene to remove the desired anilinelactone product into the organic, that is, benzene phase, then the benzene phase was separated and processed to separate the aniline-lactone product from the benzene phase.
H. Pleininger, Chemische Berichte, V. 83, p. 265-268 (1950), discusses cleavage of gamma-lactones with alkyl mercaptides. Pleininger discloses in his experimental section the conversion of dibromobutyric acid, in the absence of aniline and at low pH, to alpha-bromo-butyrolactone by heating with water at reflux temperature. Pleininger shows that the reaction between alpha-bromo-gamma-butyrolactone and aqueous ammonia gives initially gamma-hydroxy-alpha-amino butyric acid amide, which is then saponified and cyclized to alpha-amino-gamma-butyrolactone in two addition steps. In Plieninger's work, carbonyl attack (amido formation) competes with displacement of bromide (alkylation).
Frankel et al [Israel J. Chem. 1, 379-84 (1963)] found that carbonyl attack on, and resulting ring opening of, alpha-bromo-gamma-butyrolactone by aniline is favored over bromide displacement (alkylation) at high temperature (100.degree. C. vs. 0.degree. ). In Frankel, an excess of aniline was contacted with alpha-bromo-gamma-butyrolactone to give alpha-phenylamino-gamma-butyrolactone after aniline hydrobromide salt was removed. The alpha-phenylamino-gamma-butyrolactone was stirred with a 10% aqueous solution of sodium hydroxide resulting in hydrolysis or fission of the lactone ring to yield alpha-phenylamino-gamma-hydroxy butyranilide.